Venturing into the Unknown: Investigating the Role of the Lateral Septum in Mediating Female Mice Territory Behavior

Abstract

Territory exploration in animals is conducive to gain knowledge about investigated environments and evaluate social information driven by recognition of chemosensory cues. Previously, it was known that male mice display territorial behavior with urine markings and use chemosensory cues to guide exploration of novel environments. However, it is not well researched if females display similar territory expression to males. To assess whether females explore chemosensory cues similarly to males during exploration, we used a territory arena assay that featured three removable walls to divide the arena into resident, neutral, and intruder occupied areas. We recorded female and male mice locomotion across the arena during formation and exploration phases using an optical camera and captured urine markings with a thermal camera. From our results we found that males explore resident, neutral, and intruder regions at unequal proportions and females were not found to have differences in occupation between the three regions. Notably, we found a significant difference between the proportion of time spent in the resident and intruder occupied zones between males and females. We found these differences in exploration patterns may be explained by differences in urinary marking patterns between sex. However, we did not find occupancy differences between females and estrous states. To further explore the possible neural correlates involved during territory exploration, we then used wireless electrophysiology technology to record single unit activity in the lateral septum (LS) as this region has been implicated in a diverse array of functions including space encoding, social information processing, affect, and motivation. We recorded neural activity in the LS in both female and male mice when alternating between home and novel cages. Our results found selective firing patterns for each cage in both sexes. Finally, we found this cage activity unrelated to responses to novelty or valence. In summary, we found that females and males display different territory behaviors but similar neural patterns in LS when encoding cage selectivity suggesting that while LS does have a contribution to distinguishing between home and novel cage, this region of the brain likely does not drive differences in territory behavior between sex.